I wouldn't say it's exactly along the lines of Welcome to Nightvale, but another podcast that reminds me of it in some respects is "Extruding America". Like Welcome to Nightvale it pays some homage to place-as-character radio shows like Prairie Home Companion, and likewise it does it in an off-kilter and funny way. It's not hugely speculative in nature, though in later episodes it gets more so when the host of the podcasts buys a microphone that's so sensitive it can pick up thoughts and dreams. The podcast features the awesome voice talent of Eric Luke as the host Gerard Armbruster--I don't know who plays Stetson Tudd, his correspondent.

The podcast is mostly defunct since running regularly between 2006 and 2009, but every once in a while a new recording slips onto the feed--the newest one is, wow, from July 2014. I haven't heard that one yet. I don't stop by very often because the last post before that was from 2011.

Ok, so, necro-bump like whoa, but I was just recently turned on to a wee baby podcast that fits this bill crazy well. It's called Limetown, and it's currently in-progress. It's scheduled to run for seven episodes and it's really fun so far. When I was introduced I was told "It's like if Nightvale was played straight, not for laughs" and that's exactly what I'd call it.

It's spooky, creepy, and well put together. It makes you uncomfortable when it wants you to be and episode two actually scared me. Like, real, squirmy, afraid-of-the-dark scared.